Zeolite catalyst of hexagonal structure and its application

Claim 2

A catalyst comprising by weight, y% of an inorganic binder and z% of a zeolite with a structure of hexagonal symmetry related to faujasite, y and z being numbers such that 1<y<99 and 1≦z≦99 with y+z=100, the said zeolite exhibiting an Si:Al ratio ranging from 3 to 30, and parameters a, b and c of its hexagonal lattice such that 1.72 nm≦a=b≦1.75 nm and 2.80 nm≦c≦2.86 nm and corresponding to a formula which, normalized to a unit cell of the hexagonal structure, is written (uM.sub.1.sup.1+) (vM.sup.n+)(tH.sub.x O) with, in this formula, M n+ denoting cations of at least one element of valency n chosen from H, B, Al, Ga, In, the rare earth metals and the transition metals, M 1 1+ denoting cations of at least one metal of valency q chosen from the alkali metals and the alkaline-earth metals, and u, v, x and t are numbers such that t≧O depending on the degree of hydration of the zeolite, t=0 in the case of a completely anhydrous zeolite, and that qu+vn≧x with 0.5x≦vn≦x and 3<x<24.

Claim 3

The catalyst according to claim 1, wherein the proportions y% of the inorganic binder and z% of the zeolite are such that 4≦y≦96 and 4≦z≦96 with y+100.

Claim 4

The catalyst according to claim 1, wherein the zeolite, exhibits an Si:Al ratio ranging from 3 to 20.

Claim 5

The catalyst according to claim 1, characterised in that the number v of cations M n+ in the formula of the zeolite is such that 0.8x≦vn≦x.

Claim 6

The catalyst according to claim 1, characterised in that M 1 1+ in the formula of the zeolite denotes cations of at least one element chosen from Na, K, Li, Cs, Ca, Sr and Ba, while M n+ denotes cations of at least one element taken from H, B, Al, Ga, In, transition metals and rare earths.

Claim 7

The catalyst according to claim 1, characterised in that M n+ in the formula of the zeolite denotes solely H + .

Claim 8

The catalyst according to claim 1, characterised in that the zeolite present in the catalyst has a specific surface, determined by nitrogen adsorption according to the B.E.T. method simplified to a point (NF standard X 11-622), of between 100 m 2 /g and 1,000,m 2 /g.

Claim 9

The catalyst according to claim 1, characterised in that, in addition to the binder and to the zeolite, it contains up to 15% by weight of the binder and zeolite combined, of at least one catalytically active metal present in the elemental state or in the form of a metal compound and chosen from noble metals and nonnoble transition metals.

Claim 10

The catalyst according to claim 1, characterised in that the inorganic binder consists of at least one refractory oxides chosen from alumina, silica, clay, silica/alumina and magnesia.

Claim 11

The catalyst according to claim 1, wherein the zeolite present in the catalyst has a specific surface, determined by nitrogen adsorption according to the B.E.T. method simplified to a point (NF standard S 11-622), of between 300 m 2 /g and 900 m 2 /g.

Claim 12

The catalyst according to claim 1, wherein in addition to the binder and to the zeolite, it contains up to 10% by weight of the binder and zeolite combined, of at lest one catalytically active metal present in the elemental state or in the form of a metal compound and selected from the group consisting of platinum, palladium, rhodium, iridium, nickel, cobalt, tungsten, molybdenum and gallium.

Claim 13

The catalyst according to claim 1, wherein after calcination at 600° c. for 4 hours, the zeolite exhibits an X-ray diffraction pattern comparable with tat given in the following table: ______________________________________ 2θ (°) d.sub.hkl (10.sup.-1 nm) (h k l) I/Io ______________________________________ 5.88 15.03 ± 0.2 (1 0 0) VS 6.23 14.2 (0 0 2) VS 6.66 13.3 (1 0 1) S 8.40 10.52 (1 0 2) w 10.19 8.68 ± 0.08 (1 1 0) S 11.06 7.99 (1 0 3) mS 11.78 7.51 (2 0 0) mS 11.95 7.40 (1 1 2) mS 13.49 6.56 (2 0 2) vw 15.06 5.88 ± 0.05 (2 0 3) w 15.58 5.68 (0 0 5) S 15.89 5.57 (2 1 1) w 16.73 5.29 (1 0 5) w 17.18 5.16 (2 0 4) S 18.22 4.87 (2 l 3) w 18.79 4.72 (1 1 5) w 19.67 4.51 (1 0 6) w 20.45 4.34 (2 2 0) mS 22.22 4.00 (3 1 2) w 22.75 3.91 (1 0 7) w 23.30 3.82 (3 1 3) w 23.66 3.76 (3 0 5) S 24.75 3.59 (3 1 4) w 25.83 3.45 (2 2 5) w 26.52 3.36 (2 1 5) w 27.16 3.28 (4 1 0) w 28.77 3.103 ± 0.008 (3 2 4) w 30.38 2.942 (4 0 6) vw 30.89 2.894 (3 3 0) w 31.20 2.866 (5 0 3) w 31.56 2.834 (3 3 2) vw ______________________________________